Understanding on the effect of morphology towards the hydrogen and carbon monoxide sensing characteristics of tin oxide sensing elements

Though the gas sensing properties of atmospheric plasma sprayed tungsten oxide, zinc oxide, titanium oxide, tin oxide and copper oxide coatings were well investigated, reports comparing sensing characteristics of plasma sprayed sensor thick film coating with its bulk counterpart are hardly found in the literature. This work attempts to compare hydrogen and carbon monoxide sensing characteristics, namely gas response, response time, recovery time of plasma sprayed tin dioxide thick film with tin dioxide bulk sensor. Gas response in the presence of hydrogen gas (23–81%) was superior to that of carbon monoxide gas (19–79%). An attempt was made to understand plausible reason behind superior hydrogen gas response. Thus, gas response as a function of temperature was simulated using a gas diffusion equation for hydrogen and carbon monoxide gases. Estimated parameters, namely, activation energy of transduction and first order kinetics were correlated with sensor microstructure and experimental gas response values. For hydrogen sensing, shorter response time (30–138 s) and recovery time (118–161 s) of thick film as compared to response time (64–234 s) and recovery time (183–196 s) of bulk sensor was correlated with microstructure of sensory elements. It was observed that tin dioxide thick film, owing to its porous morphology with small-sized particulates exhibited superior hydrogen gas response, short response time and recovery time as compared to its bulk counterpart.     

Prenatal diagnosis with ultrasound of anomalous course of the umbilical vein and its relationship to fetal outcome

Diagnosis of three types of anomalous course of the umbilical vein (UV) was made in 10 cases using antenatal ultrasound (US). Pulsed wave (PW) Doppler ultrasound was used to evaluate the UV in all cases. In one case, the UV was directly joining the superior vena cava (SVC) without forming subcutaneous collaterals, an abnormal course of UV not yet reported previously. Of these ten fetuses, six had various associated anomalies, including three fetuses with central nervous system (CNS) abnormalities.     

Electrophoretic deposition of CuO particulate thick film for ethanol sensing

Journal of Materials Science: Materials in Electronics - Detection of volatile organic compounds is of utmost importance in numerous applications such as medical diagnosis, air quality monitoring,...     

Improved dielectric performance of polypropylene/multiwalled carbon nanotube nanocomposites by solid‐phase orientation

By means of a die‐drawing technique in the rubbery state, the effect of the orientation of the microstructure on the dielectric properties of polypropylene (PP)/multiwalled carbon nanotube (MWCNT) nanocomposites was examined in this study. The viscoelastic behavior of the PP/MWCNT nanocomposites with MWCNT weight loadings ranging from 0.25 to 5 wt % and the dielectric performance of the stretched PP/MWCNT nanocomposites at different drawing speeds and drawing ratios were studied to obtain insight into the influences of the dispersion and orientation state of the MWCNTs and matrix molecular chains. A viscosity decrease (ca. 30%) of the PP/MWCNT‐0.25 wt % (weight loading) melt was obviously due to the free volume effect. Differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction were adopted to detect the orientation structure and the variation of crystal morphology of the PP/MWCNTs. Melting plateau regions, which indicated the mixed crystallization morphology for the stretched samples, were found in the DSC patterns instead of a single‐peak for the unstretched samples. We found that the uniaxial stretching process broke the conductive MWCNT networks and consequently increased the orientation of MWCNTs and molecular chains along the tensile force direction; this led to an improvement in the dielectric performance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42893.